[Ovirt-devel] [PATCH server] Use DNS SRV records for qpidd on appliance

[Ian Main]

This patch makes taskomatic and dbomatic etc. use dns srv records
when connecting to qpidd.  This fixes the installer problems we
were seeing when connecting to various host names.

Signed-off-by: Ian Main <imain at redhat.com>
---
 src/db-omatic/db_omatic.rb    |    6 +++++-
 src/dutils/dutils.rb          |   32 ++++++++++++++++++++++++++++++++
 src/qmf-libvirt-example.rb    |    5 ++++-
 src/task-omatic/taskomatic.rb |    7 +++++--
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/src/db-omatic/db_omatic.rb b/src/db-omatic/db_omatic.rb
index 06adc19..845a714 100755
--- a/src/db-omatic/db_omatic.rb
+++ b/src/db-omatic/db_omatic.rb
@@ -327,8 +327,12 @@ def main()
     get_credentials('qpidd')
 
     dbsync = DbOmatic.new()
+
+    server, port = get_srv('qpidd', 'tcp')
+    raise "Unable to determine qpid server from DNS SRV record" if not server
+
     s = Qpid::Qmf::Session.new(:console => dbsync, :rcv_events => false)
-    b = s.add_broker("amqp://management.priv.ovirt.org:5672", :mechanism => 'GSSAPI')
+    b = s.add_broker("amqp://#{server}:#{port}", :mechanism => 'GSSAPI')
 
     dbsync.db_init_cleanup()
 
diff --git a/src/dutils/dutils.rb b/src/dutils/dutils.rb
index 6df2f06..5b2ac50 100644
--- a/src/dutils/dutils.rb
+++ b/src/dutils/dutils.rb
@@ -18,6 +18,8 @@
 
 require 'active_record_env'
 require 'krb5_auth'
+require 'resolv'
+
 include Krb5Auth
 
 ENV['KRB5CCNAME'] = '/usr/share/ovirt-server/ovirt-cc'
@@ -56,3 +58,33 @@ def get_credentials(service = 'libvirt')
     end
   end
 end
+
+# Returns the server and port of the specified service using DNS SRV records
+# to perform the look up.
+#
+# For example:
+#
+# server, port = get_srv('qpidd', 'tcp')
+#
+def get_srv(service, proto)
+  server = nil
+  port = nil
+
+  Resolv::DNS.open do |dns|
+    begin
+      hostname = Socket.gethostbyname(Socket.gethostname).first
+      lst = hostname.split('.')
+      lst.shift
+      domainname = lst.join('.')
+      res = dns.getresource("_#{service}._#{proto}.#{domainname}", Resolv::DNS::Resource::IN::SRV)
+      server = res.target.to_s
+      port = res.port
+    rescue => ex
+      puts "Error looking up SRV record: #{ex}"
+    end
+    dns.close
+  end
+
+  return server, port
+end
+
diff --git a/src/qmf-libvirt-example.rb b/src/qmf-libvirt-example.rb
index f8d6aca..64e3ba7 100644
--- a/src/qmf-libvirt-example.rb
+++ b/src/qmf-libvirt-example.rb
@@ -8,8 +8,11 @@ require "dutils"
 
 get_credentials('qpidd')
 
+server, port = get_srv('qpidd', 'tcp')
+raise "Unable to determine qpid server from DNS SRV record" if not server
+
 s = Qpid::Qmf::Session.new()
-b = s.add_broker("amqp://management.priv.ovirt.org:5672", :mechanism => 'GSSAPI')
+b = s.add_broker("amqp://#{server}:#{port}", :mechanism => 'GSSAPI')
 
 while true:
     nodes = s.objects(:class => "node")
diff --git a/src/task-omatic/taskomatic.rb b/src/task-omatic/taskomatic.rb
index 79e2082..77fe6da 100755
--- a/src/task-omatic/taskomatic.rb
+++ b/src/task-omatic/taskomatic.rb
@@ -47,8 +47,11 @@ class TaskOmatic
     @nth_host = 0
 
     @session = Qpid::Qmf::Session.new()
-    # FIXME: Should come from some kind of config or DNS SRV or what have you.
-    @broker = @session.add_broker("amqp://management.priv.ovirt.org:5672", :mechanism => 'GSSAPI')
+
+    server, port = get_srv('qpidd', 'tcp')
+    raise "Unable to determine qpid server from DNS SRV record" if not server
+
+    @broker = @session.add_broker("amqp://#{server}:#{port}", :mechanism => 'GSSAPI')
 
     do_daemon = true
 
-- 
1.6.0.4